At 18.25 hours on 25 Aug 1942, U-164 fired two torpedoes at the Stad Amsterdam (Master D.J. Boog), which was a straggler from convoy WAT-15 due to engine troubles. At least one torpedo hit as a dud (apparently the torpedoes were fired from too close range) because it was noticed how the ship stopped and slowly developed a list to port. At 22.03 hours, a coup de grâce hit aft and caused the ship to sink by the stern after a first coup de grâce had missed three minutes earlier. The survivors abandoned ship in two lifeboats and were questioned by the U-boat.